Troubleshooting Error Importing Vertex Protocol SDK Module Not Found

Introduction

Encountering issues when importing an SDK can be a significant roadblock in your development process. This article addresses a common problem faced by developers using the Vertex Protocol SDK in a NodeJS + TypeScript project: the dreaded "Cannot find module" error. This issue typically arises after installing the @vertex-protocol/client package and attempting to import modules like createVertexClient. This comprehensive guide delves into the root causes, potential solutions, and best practices to resolve this problem effectively, ensuring a smooth integration of the Vertex Protocol SDK into your projects.

Problem Description

Many developers have reported encountering an error when trying to import modules from the @vertex-protocol/client package. The error message usually looks like this:

Error: Cannot find module '/path/to/project/node_modules/@vertex-protocol/client/dist/createVertexClient' imported from /path/to/project/node_modules/@vertex-protocol/client/dist/index.js

This error occurs despite having installed the necessary packages (@vertex-protocol/client, viem, and bignumber.js) using npm install. The problem seems to stem from the migration of the project from CommonJS to ESM (ECMAScript Modules), which requires explicit file extensions in import statements.

Detailed Scenario

The issue typically arises in a NodeJS + TypeScript project configured with the following:

• Node.js: v24
• ts-node: "^10.9.2"
• TypeScript: "^5.8.3"
• @vertex-protocol/client: "^1.14.0"

The steps to reproduce the error are straightforward:

1. Create a new NodeJS + TypeScript project.
2. Run npm install @vertex-protocol/client viem bignumber.js.
3. Attempt to import the SDK using:

   import { createVertexClient } from "@vertex-protocol/client";
   

4. The "Cannot find module" error appears.

Root Causes

The primary cause of this issue is the transition of the Vertex Protocol SDK from CommonJS to ESM format. ESM requires that import statements include the file extension (e.g., .js) when importing modules. If the build output of the SDK does not include these extensions in the import paths, Node.js will fail to resolve the modules, leading to the ERR_MODULE_NOT_FOUND error.

ESM and File Extensions

ESM mandates explicit file extensions in import specifiers. For instance, if you have a file createVertexClient.js, you must import it as:

import { createVertexClient } from "./createVertexClient.js";

Omitting the .js extension will result in a module resolution error. This requirement ensures clarity and avoids ambiguity in module loading.

Missing File Extensions in SDK Build Output

When examining the build output of the @vertex-protocol/client package (specifically, the dist directory), it’s often found that the import statements lack the necessary .js extensions. For example, the index.js file might contain:

export * from './createVertexClient';

Instead of the correct:

export * from './createVertexClient.js';

This discrepancy causes Node.js to fail in resolving the module, as it cannot find createVertexClient without the explicit .js extension.

Solutions and Workarounds

Several approaches can be taken to resolve this issue, ranging from temporary workarounds to more permanent fixes. Let's explore these solutions in detail.

Manual Modification (Temporary Workaround)

One immediate but temporary solution is to manually modify the import statements within the node_modules/@vertex-protocol/client/dist directory. By adding the .js extension to each import statement, you can bypass the module resolution error. For example, change:

export * from './createVertexClient';

to:

export * from './createVertexClient.js';

While this workaround can get your project running, it is not a sustainable solution for the long term. Any updates to the @vertex-protocol/client package will overwrite these manual changes, requiring you to reapply them. Therefore, it’s crucial to look for a more permanent fix.

Verifying and Adjusting tsconfig.json

Your TypeScript configuration (tsconfig.json) plays a crucial role in how your project handles modules. Ensure that your tsconfig.json is correctly configured for ESM. Here are some key settings to verify:

• module: This should be set to esnext or Node16 to support ESM.
• moduleResolution: Setting this to node or Node16 tells TypeScript to use Node.js-style module resolution, which is essential for ESM.
• target: Ensure this is set to a modern ECMAScript version (e.g., es2020 or later).
• esModuleInterop: Setting this to true is often necessary to handle compatibility between CommonJS and ESM modules.
• declaration: This setting should generally be enabled to generate declaration files (.d.ts), which improve the TypeScript experience.

Here’s an example of a tsconfig.json configuration that is suitable for an ESM project:

{
  "compilerOptions": {
    "target": "es2020",
    "module": "esnext",
    "moduleResolution": "Node16",
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "skipLibCheck": true,
    "declaration": true,
    "outDir": "dist"
  },
  "include": ["src/**/*"]
}

Package Type in package.json

The type field in your package.json file dictates whether your project uses CommonJS or ESM. Ensure that this is correctly set. If you intend to use ESM, add or modify the type field as follows:

{
  "type": "module",
  // other configurations
}

If this field is not set or is set to `